<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8" />
		<title></title>
	</head>
	<body>
		
	</body>
	<script>
		var a=10;
	var b=20;
	var c = Number(a) + Number(b) 
	var d =parseInt(a)+parseInt(b)
	alert("a+b="+a+b);//1020
	alert("c="+c);//30
	alert("d="+d);//30
	alert("a+b="+Number(a) + Number(b) );1020//
	</script>
</html>
